International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 04 | Apr-2018 www.irjet.net p-ISSN: 2395-0072 Study of solar-thermal collector assisted hybrid split air conditioner Chetan Brahmankar1, Hrishikesh Bhushan2, Akshay Ghule3, Himanshu Ranjan4 1,2,3,4 Dept. of mechanical engineering, Dr. D.Y Patil Institute of Technology, Maharashtra, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - In this paper we used the solar thermal collector The objectives of this study are to design and integrate solar to reduce the electricity consumption of compressor. hybrid system into conventional air conditioning system, to Compressor which is the most electricity-consuming unit of air reduce air conditioning electricity consumption by up to conditioner essentially, compresses low-pressure fluid which in 45%, and to reduce electricity peak load during the day. turn gets heated. A solar collector panel can assist in heating the fluid and thus can reduce the load on the compressor, 2. EVACUATED TUBE which in turn will reduce the electricity consumption. In a typical house using air conditioners, the electricity required A variety of technologies exist to capture solar radiation, for cooling can be as high as 30% of the total electricity used but of particular interest of authors is evacuated tube in commercial complexes, this percentage is even higher. technology. Numerous authors have noted that ETSCs have much greater efficiencies than the common FPC, especially at The study analyzed the performance of solar-thermal collector low temperature and isolation. For instance, Ayompe et al. assisted hybrid split air conditioner and conventional Conducted a field study to compare the performance of an electricity powered air conditioner, compare energy FPC and a heat pipe ETSC for domestic water heating system. performance and evaluate energy saving due to solar-thermal With similar environmental conditions, the collector collector assisted hybrid split air conditioner. Solar collector efficiencies were found to be 46.1% and 60.7% and the absorbs sunlight and converts to usable heat. The evacuated system efficiencies were found to be 37.9% and 50.3% for tube prevents the loss of heat from plate to surrounding when FPC and heat pipe ETSC, respectively. An ETC is made of there is temperature difference between inside of the tube and parallel evacuated glass pipes. Each evacuated pipe consists the outside ambient air. of two tubes, one is inner and the other is outer tube. The inner tube is coated with selective coating while the outer We are able to reduce the electricity consumption of air tube is transparent. Light rays pass through the transparent conditioner close to 30% which in turn reduces CO2 emission of outer tube and are absorbed by the inner tube. Both the thermal power plant. inner and outer tubes have minimal reflection properties. The inner tube gets heated while the sunlight passes through Key Words: Hybrid Air Conditioner, Evacuated tube, the outer tube and to keep the heat inside the inner tube, a solar collector, Energy Saving, R410a vacuum is created which allows the solar radiation to go through but does not allow the heat to transfer. In order to 1. INTRODUCTION create the vacuum, the two tubes are fused together on top and the existing air is pumped out. Thus the heat stays inside Solar energy is one of the most available forms of energy on the inner pipe sand collects solar radiation efficiently. the Earth’s surface, besides; it is very promising and Therefore, an ETSC is the most efficient solar thermal generous. The earth’s surface receives a daily solar dose of collector. An ETSC, unlike an FPC, can work under any 10E+8 KW-hr, which is equivalent to 500 000 billion oil weather conditions while it provides acceptable heat barrels that is one thousand times any oil reserve known to efficiency. man. 2.1 Why an evacuated tube solar collector (ETSC) is The demand of air conditioning has greatly increased since preferable? the last decade due to the effect of climate change and global warming. High fuel price and electric tariff makes The single-walled glass evacuated tube is popular in conventional air conditioner not economical in the long run. Europe. Badar et al studied the thermal performance of an Furthermore, generating electricity from fossil fuel emits individual single walled evacuated tube with direct flow greenhouse gases and worsen the global warming. This type coaxial piping based on analytical steady state model. paper presents the investigation into the feasibility of solar Kim et al investigated the thermal performance of an assisted vapour compression air conditioning system in ETSC with four different shaped absorbers both providing thermal comfort in India. Solar energy is harvested experimentally and numerically. Four different shapes are: through solar collector which provides part of compression finned tube (Model I), tube welded inside a circular fin pressure by heating the refrigerant under constant volume, (Model II), U tube welded on a copper plate (Model III) and thus reducing energy consumption by lowering the load on U tube welded inside a rectangular duct .Firstly, by the electric compressor. considering only the beam radiation, the performance of a single collector tube was observed and it was found that the incidence angle has great influence on the collector © 2018, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 2921 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 04 | Apr-2018 www.irjet.net p-ISSN: 2395-0072 efficiency. Model III had the highest efficiency with small ------(2) incidence angle but the efficiency of model II became higher than model III with the increment of incidence Process 3-4: Throttling and expansion angle. The incidence angle has negligible impacts on collector performance while considering the diffuse An irreversible throttling process in which the radiation and the shadow effects and model III is found to temperature and pressure decrease at constant enthalpy. have the best performance for all ranges of the incidence angle. -----(3) 3. Solar Hybrid Air Conditioning System Process 4-1: Evaporation An internally, reversible, constant pressure heat interaction in which the refrigerant is evaporated to a saturated vapour at state point 1 --------(4) The thermal efficiency of the cycle can be calculated as: ------(5) Figure 1. Solar Hybrid Air Conditioning System Figure 1 shows the evacuated tube solar collector is installed between the compressor and condenser. The solar collector consists of high efficient vacuum tube which provides part of compression pressure and heating by further superheating the refrigerant. The higher pressure and larger temperature difference enhance the condensation process in the condenser, resulting in high pressure liquid refrigerant. This configuration greatly reduces energy consumption by reducing the load on electric compressor. 3.1 Refrigerant Cycle During refrigeration process, the refrigerant experiences Figure 2. T-s diagram of vapour compression huge change in thermodynamic properties and involves heat refrigeration cycle energy transfer to the surroundings through the heat exchangers [5]. During the operation of a vapour 3.2 Solar Hybrid Vapour Compression compression refrigeration system, the following processes Refrigeration Cycle. occurs as shown in Figure 2 Process 1-2s: Compression The evacuated tube solar collector is installed between the compressor and condenser, providing part of compression A reversible, adiabatic (isentropic) compression of the pressure and heating by further superheating the refrigerant. The saturated vapour at state 1 is superheated to refrigerant. Figure 5 shows the parameters of solar hybrid state 2. ------(1) Process 2s-3: Condensation An internally, reversible, constant pressure heat rejection in which the refrigerant is de-superheated and then condensed to a saturated liquid at state point 3. © 2018, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 2922 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 04 | Apr-2018 www.irjet.net p-ISSN: 2395-0072 3.4 Single walled glass evacuated tube The solar collector provides part of compression pressure by heating the refrigerant under constant volume. Ideal gas law states that PV=nRT, where P is absolute pressure of gas, V is volume of gas, n is number of moles of gas, R is ideal gas constant, and T is absolute temperature of gas. During the 2nd stage compression, V, n, and R are kept constant, deriving the ideal gas law into is the input pressure, is input temperature, is the output pressure, and is output temperature. Therefore, the higher the temperature of solar collector, the higher the pressure of refrigerant. Figure 5: Diagram of solar hybrid vapour compression refrigeration cycle Where T and S are Temperature and entropy respectively Point 1: P1, T1 :Evapotator Outlet Point 2: P2,T2 :Compressor Outlet Point 3: P3,T3 :Solar Plate outlet Figure 3. Evacuated Tube Solar Collector Point 4: P4,T4 :Condenser Inlet Evacuated tube solar collectors consists of series of glass Point 5: P5,T5 : Evaporator Inlet tubes which has the air evacuated out, creating a vacuum Where, P and T are Pressure and temperature. between the glass tube surface and